Manitoba

'Clean, drain, dry' boats or risk being fined for spreading zebra mussels

With fishing and swimming season upon us, the province is reminding recreational boaters to be extra cautious about spreading zebra mussels in Manitoba’s lakes and streams, as they can survive out of water anywhere from a week to a month.

Invasive species can survive out of water on boats, ATVs, float planes for 7-30 days

Zebra mussels coat a boat's stainless steel trim tab and cylinder in Gimli Harbour. (Submitted by Dean Thorkelsson)

With fishing and swimming season upon us, the province is reminding recreational boaters to be extra cautious about accidentally spreading zebra mussels in Manitoba's lakes and streams, as they can survive out of water anywhere from a week to a month.

It's been three years since the invasive species was first detected in Lake Winnipeg, and zebra mussels have already spread into the Red River and Cedar Lake. The province is focusing its efforts this year on trying to keep zebra mussels from spreading outside of those three bodies of water, and they're leaning on new legislation to help.

That's no small feat, considering how quickly the species reproduces and how long it can survive stuck to boat hulls out of water.

Candace Parks, an aquatic invasive species expert with Manitoba Sustainable Development, said rather than being limited to checking watercraft at boat launches, the new legislation lets officials with the province set up highway checkpoints it hopes will help curb the spread of the species. 

Boaters found giving zebra mussels a free ride from waterway to waterway.

'We were quite startled'

Zebra mussels were first detected in the south basin of Lake Winnipeg in 2013, and last summer they were found in the north basin for the first time. In June 2015, they were found in the Red River near Emerson, Man.

"We were quite startled by what we found there, because we had been monitoring the Red River since 2009," Parks said. "That was eye-opening for us."

The invasion of veligers, which are the "baby phase of zebra mussels," into Cedar Lake has scientists most worried at the moment, Parks said. While the larval phase of the species can't survive out of water nearly as long as the adults, finding them in an aquatic ecosystem is usually an early warning sign of what's to come.

"It's the most concerning because the flow of water is through the Saskatchewan River, through Cedar Lake and into Lake Winnipeg," Parks said, adding the baby mussels can't swim on their own and rely on currents — or boats, ATVs and float planes — to get around.

"We can say with 100 per cent certainty a human has now brought zebra mussels from an invaded water body and introduced them into Cedar Lake," she said. "There is no natural way the veligers would've gotten there on their own."

The province is trying to drill the "clean, drain, dry" message into boaters right now. What that means is boaters should thoroughly spray down and scrub boats that leave any body of water in the province, then pull out all plugs and drain them fully before drying them and driving off.

"We can slow the spread and that's absolutely critical," she said. "This is completely preventable if people take the proper steps."

Zebra mussels have no native predators in any of the three bodies of water they've invaded in Manitoba. They can clog water treatment infrastructure and wreak havoc on the health of species indigenous to Lake Winnipeg, the Red River and Cedar Lake.

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